Hi wenxu, I think we're almost there. There are some improvements still possible, but could be included in later patches. Theoretically, we should perform the first lookup with the orig_ports and then start with random sub ranges. The current patch doesn't do that, but we can leave this as a further improvement.
[email protected] writes: > From: wenxu <[email protected]> > > In case almost or all available ports are taken, clash resolution can > take a very long time, resulting in pmd hang in conntrack. > > This can happen when many to-be-natted hosts connect to same > destination:port (e.g. a proxy) and all connections pass the same SNAT. > > Pick a random offset in the acceptable range, then try ever smaller > number of adjacent port numbers, until either the limit is reached or a > useable port was found. This results in at most 248 attempts > (128 + 64 + 32 + 16 + 8, i.e. 4 restarts with new search offset) > instead of 64000+. > > And if thenumber of ip address will limit the max attempts and which > will lead the total attempts under 248. > > Signed-off-by: wenxu <[email protected]> > --- > lib/conntrack.c | 60 > ++++++++++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 53 insertions(+), 7 deletions(-) > > diff --git a/lib/conntrack.c b/lib/conntrack.c > index dc29c9b..4079a35 100644 > --- a/lib/conntrack.c > +++ b/lib/conntrack.c > @@ -2400,13 +2400,18 @@ next_addr_in_range_guarded(union ct_addr *curr, union > ct_addr *min, > static bool > nat_get_unique_l4(struct conntrack *ct, struct conn *nat_conn, > ovs_be16 *port, uint16_t curr, uint16_t min, > - uint16_t max) > + uint16_t max, unsigned int *round, > + unsigned int attempts) > { > FOR_EACH_PORT_IN_RANGE(curr, min, max) { > - *port = htons(curr); > - if (!conn_lookup(ct, &nat_conn->rev_key, > - time_msec(), NULL, NULL)) { > - return true; > + if ((*round)++ < attempts) { > + *port = htons(curr); > + if (!conn_lookup(ct, &nat_conn->rev_key, > + time_msec(), NULL, NULL)) { > + return true; > + } > + } else { > + break; > } > } > > @@ -2446,6 +2451,10 @@ nat_get_unique_tuple(struct conntrack *ct, const > struct conn *conn, > uint16_t min_dport, max_dport, curr_dport, orig_dport; > bool pat_proto = conn->key.nw_proto == IPPROTO_TCP || > conn->key.nw_proto == IPPROTO_UDP; > + unsigned int attempts, max_attempts, min_attempts; > + uint16_t range_src, range_dst, range_max; > + uint32_t range_addr; > + unsigned int i; > > min_addr = nat_info->min_addr; > max_addr = nat_info->max_addr; > @@ -2462,6 +2471,24 @@ nat_get_unique_tuple(struct conntrack *ct, const > struct conn *conn, > set_dport_range(nat_info, &conn->key, hash, &orig_dport, > &min_dport, &max_dport); > > + range_src = max_sport - min_sport + 1; > + range_dst = max_dport - min_dport + 1; > + range_max = range_src > range_dst ? range_src : range_dst; > + if (conn->key.dl_type == htons(ETH_TYPE_IP)) { > + range_addr = ntohl(max_addr.ipv4) - ntohl(min_addr.ipv4) + 1; > + } else { > + range_addr = nat_ipv6_addrs_delta(&nat_info->min_addr.ipv6, > + &nat_info->max_addr.ipv6) + 1; > + } > + max_attempts = 128 / range_addr; > + if (max_attempts < 1) { > + max_attempts = 1; > + } > + min_attempts = 16 / range_addr; > + if (min_attempts < 2) { > + min_attempts = 2; > + } > + can you put the code of this hunk in a function? I think it could improve a bit the readability. Please use min_addr and max_addr instead of nat_info when calculating the addr ranges. > another_round: > store_addr_to_key(&curr_addr, &nat_conn->rev_key, > nat_info->nat_action); > @@ -2481,24 +2508,43 @@ another_round: > nat_conn->rev_key.src.port = htons(curr_dport); > nat_conn->rev_key.dst.port = htons(curr_sport); > > + attempts = range_max; > + if (attempts > max_attempts) { > + attempts = max_attempts; > + } > + > +another_port_round: > + i = 0; > + > bool found = false; > if (nat_info->nat_action & NAT_ACTION_DST_PORT) { > found = nat_get_unique_l4(ct, nat_conn, &nat_conn->rev_key.src.port, > - curr_dport, min_dport, max_dport); > + curr_dport, min_dport, max_dport, &i, is there any reason you pass &i instead of using a local variable in nat_get_unique_l4()? > + attempts); > if (!found) { > + i = 0; > nat_conn->rev_key.src.port = htons(orig_dport); > } > } > > if (!found) { > found = nat_get_unique_l4(ct, nat_conn, &nat_conn->rev_key.dst.port, > - curr_sport, min_sport, max_sport); > + curr_sport, min_sport, max_sport, &i, > + attempts); > } > > if (found) { > return true; > } > > + if (attempts < range_max && attempts >= min_attempts) { > + attempts /= 2; > + curr_dport = min_dport + (random_uint32() % range_dst); > + curr_sport = min_sport + (random_uint32() % range_src); > + > + goto another_port_round; > + } > + > /* Check if next IP is in range and respin. Otherwise, notify > * exhaustion to the caller. */ > next_addr: > -- > 1.8.3.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
